A new functional composite material based on lithium vanadium oxide for high performance energy storage and conversion applications

Abstract

Originally reported in 1957, monoclinic lithium vanadium oxide (LiV₃O₈, LVO) continues to attract researchers due to its potential across various applications. In this study, LVO and carbon encapsulated LVO (C-LVO) were synthesized via a simple, cost-effective two-step hydrothermal process, and their multifunctional properties for various energy applications were analyzed for the first time. The materials exhibited a mixed phase of LiV₃O₈ and LiV₂O₅, offering several advantages, particularly interests for their use in a symmetrical cell. The free-standing LVO and C-LVO electrodes were prepared using a surface-engineered tape casting method. The C-LVO electrode displayed an initial discharge capacity of 344 mAh/g between 1.5 and 4 V at 1 C, and 533 mAh/g between 0.01 and 3 V at 1 C, respectively. Furthermore, the symmetric full-cell assembled with these electrodes demonstrated a high energy density of 473 Wh/kg and a substantial power density of 1007 W/kg. Over 1000 cycles at 5 C, the symmetric full-cell maintained an impressive 93 % retention of its initial discharge capacity, alongside a consistent 100 % coulombic efficiency. Beyond battery analysis, the multifunctional properties of LVO were further examined for lithium-ion capacitor (LIC) and solid oxide fuel cell (SOFC) applications. The LIC device exhibited an impressive 83 % capacity retention after 5000 cycles, demonstrating outstanding long-term stability. Additionally, the high ionic conductivity (σ = 7 × 10⁻¹ S/cm) and low activation energy (E_a = 0.99 eV) of the 95Ce-LVO solid electrolyte highlighted its potential for low and intermediate temperature SOFC applications.